package LianXi;

import java.util.Scanner;

public class L6 {
	public static void main(String[] args) {
		Scanner input=new Scanner(System.in);
		int sum=0;
		
		for(int i=1;i<=100;i++) {
			
		if(i%3!=0) {
			sum+=i;
			
		}
	
		}
		System.out.println(sum);
		
	}

}
